Perspective: Multireference coupled cluster theories of dynamical electron correlation.

Area of Science:

• Quantum chemistry
• Theoretical chemistry
• Computational physics

Background:

• Strong electron correlation poses a significant challenge in accurately predicting molecular electronic structure and properties.
• Traditional methods like configuration interaction and perturbation theory often fail to capture these complex correlation effects.

Purpose of the Study:

• To review recent advancements in multireference wave function methods for describing dynamical electron correlation.
• To highlight current challenges and future directions in developing systematically improvable methods.

Main Methods:

• Focus on multireference wave function approaches.
• Discussion of methods that systematically improve upon configuration interaction and perturbation theory.
• Exploration of techniques designed to handle strong electron correlation effects.

Main Results:

• Recent progress in developing advanced multireference wave function methods has been made.
• These methods offer improved accuracy for systems with strong electron correlation.
• Systematically improvable approaches are emerging to address limitations of older theories.

Conclusions:

• Multireference wave function methods are crucial for tackling strong electron correlation problems.
• Continued development of systematically improvable methods is essential for accurate theoretical predictions.
• These advanced techniques promise to enhance our understanding of complex molecular systems.